This invention relates to a warp yarn sizing composition utilized in the manufacturing process for textiles and more particularly, to an improved warp yarn sizing composition suitable for use in the manufacture of fabric, particularly denim, comprising a noncongealing, hydrophilic, starch derivative exhibiting a five gram alkali fluidity of from about 10 milliliters to about 97 milliliters and from about 0 to about 80 wt % of a thin boiling starch.
In the course of manufacturing textiles, fiber materials are woven together to form a cloth. In the weaving operation feed yarn, referred to as warp yarn, is fed by a loom. A weaving yarn, referred to as a filling yarn, is woven in between the individual warp yarns to form a fabric. During this operation there is considerable abrasion between the warp yarn and filling yarn sometimes resulting in breakage and an inefficient weaving operation. To reduce abrasion between the warp yarn and the filling yarn, the warp yarn is sized with a warp yarn sizing composition. Many warp sizing materials are used in the manufacture of textile fabrics, particularly denim. Heretofore, the main property sought to be controlled by sizing warp utilized in the manufacture of denim was the abrasion reduction between the warp yarn and the filling yarn during the weaving operation. While other properties imparted to the fabric by use of a sized warp yarn such as stiffness and strength are pertinent, the primary property that the sized warp yarn must possess is the ability to reduce abrasion.
There are many warp yarn sizing compositions known in the art. For example, thin-boiling starches have been utilized as warp yarn sizing materials. It has been found, however, that while thin-boiling starches provide desired abrasion resistance during the weaving operation, they must be maintained and utilized at a temperature of not less than 180.degree. F. Failure to maintain thin-boiling starches above this temperature results in the starches becoming congealed which adversely affects the ability of the starch to adhere to the warp yarn prior to a weaving operation. Additionally, the congealed starch loses adhesive strength.
Similarly, polyvinyl alcohol (PVA) also has been utilized as a warp yarn sizing composition. However, it is relatively expensive and, in some instances, gives irregular appearance to a fabric upon subsequent fabric washing and cleaning.
When a denim material or fabric is manufactured, the woven fabric is shipped directly to the garment manufacturer following a weaving operation and following a subsequent finishing process such as sanforizing or finish sizing. The woven denim is relatively stiff from incorporation of the warp yarn sizing composition and this stiffness serves to facilitate cutting and sewing operations performed to complete a denim garment. After the denim garment is formed, it is laundered to remove the warp yarn sizing composition to achieve a relatively soft hand form of the garment as required by market demands. The laundering operation is substantially costly due to the fact that commercially available warp yarn sizing compositions are water insoluble. This water insolubility presents a problem in that the wash of the denim garment following manufacture requires a laundry cycle which utilizes elevated temperatures, chemicals, and an extended duty cycle, typically thirty-eight minutes, to achieve sufficient removal of the warp yarn sizing composition to provide an acceptable soft hand form of the denim garment.
Because of the limited number of commercial laundries, the laundering operation is a production inhibiting step not only for soft hand form denim garments, but also for garments subsequently formed from soft hand form denim such as bleached and stonewashed denim garments. Further, the appearance of these garments may be adversely affected by non-uniform removal of the warp yarn sizing.
What is desired is to have a material which provides the desired abrasion resistance and stiffness properties, can be utilized in a warp yarn sizing operation, is relatively inexpensive and is sufficiently water soluble to permit a significantly shortened laundry cycle at lower temperatures without detergents. The sizing material when used with a denim fabric should provide a soft hand form denim garment and improved appearance due to facilitating pressing and handling operations following the laundry cycle.
Additionally, it is important that the material be removed uniformly during the laundry cycle so that subsequent bleaching and stonewashing operations do not adversely affect the appearance of the denim garment.